It is possible to use a system property in ehcache3.xml when configuring the cluster url? like:
<terracotta:connection url="${ehcache.cluster.server}" />
This is currently not possible as-is because there is an XSD validation on that field, which prevents the value from starting with such characters.
However, you can trick that XSD validation by doing the following:
<terracotta:connection url="terracotta://${ehcache.cluster.server}" />
and make sure to not have the terracotta://
in your system prop value.